Roadway repair is often accomplished by overlaying the existing pavement (whether of concrete or asphalt paving material) with a new layer (often called a leveling course) of concrete or asphalt paving material. Without prior surface treatment, however, this method of repair generally results in the application of insufficient quantities of paving material in the rutted, potholed or otherwise damaged areas, because the overlay will be applied at the same rate per unit of roadway width in damaged areas (which have a greater depth to be filled across the width) as in the undamaged areas. The resulting reduced thickness in the overlay of the previously damaged areas will lead to renewed rutting or other wear damage in the new pavement in relatively short order. However, by milling the surface of the damaged pavement to a uniform surface elevation below the level of the damage, the addition of a new pavement overlay will produce a road surface having a consistent elevation across the entire width of the roadway. This repaving technique can be used to return the elevation of a damaged roadway to its original pre-damaged elevation, whereas the placement of a leveling course atop damaged but un-milled pavement will tend to raise the surface of the roadway or some portion thereof above its original elevation. Roadway repair without milling can require the raising of road shoulders, guardrails and manhole covers and the adjustment of overpass clearances, all of which is unnecessary if a proper milling technique is employed. A use of milling prior to repaving can also permit ready establishment of the proper road grade and slope, and thereby avoid drainage and safety problems. Furthermore, milling typically provides a rough surface that readily accepts and bonds with the new asphalt or other pavement overlay. Finally, milling can provide raw material that can be reclaimed for use in the production of new paving materials.
A milling machine typically comprises a wheel-driven or track-driven vehicle that includes a milling drum having a plurality of cutting teeth around its periphery. The milling drum is mounted for rotation about a substantially-horizontal axis within a drum housing on the frame of the machine. Steerable wheel-drive or track-drive assemblies operated by hydraulic motors are provided to drive the machine in a milling direction and to steer it along a desired milling path. The drive assemblies are attached to lifting columns that include internal linear actuators which can be activated to raise and lower the frame of the machine with respect to the roadway surface. Milling machines are provided in various sizes so as to be able to produce a cut on the roadway ranging in width from about 6 feet to about 13.5 feet. Generally, the milling machine also includes a conveyor system that is designed to carry the majority of the milled material that has been cut from the roadway by the rotating drum to a location in front of, to the rear of, or beside the machine for deposit into a truck for removal from the milling site. Sweeping machines are frequently required, however, to follow a milling machine in order to remove any milled material left behind by the milling machine prior to resurfacing.
Conventional sweeping machines typically employ a broom assembly comprising one or more brooms mounted for rotation about horizontal or vertical axes. Some conventional machines may operate by pushing the swept material to one side of the machine where it may be collected by a separate collecting device. Other conventional machines include a broom assembly and an integral collecting assembly for collecting material swept by the broom or brooms. Such integral collecting assemblies may comprise vacuum systems for capturing the material swept by the brooms or discharge conveyors for transporting such material to a hopper or an adjacent truck.
Some conventional sweeping machines include broom assemblies which employ permanent brooms, while others employ replaceable brooms. Typically, a replaceable broom comprises a cylindrical broom tube of steel or other durable material having a plurality of bristles disposed around its outer periphery. Conventional sweeping machines that employ replaceable brooms typically hold the broom tube inside the machine with a pair of drive hubs, one on each end. These hubs are typically mounted in bearings that are bolted or otherwise attached to arms on the sweeping assembly that may be raised or lowered to move the broom into and out of contact with the roadway. Because of the way that conventional broom assemblies are mounted to the sweeping machine, the width of the broom assembly (i.e., the dimension of the broom assembly that is transverse to the forward sweeping direction, as hereinafter defined) cannot be adjusted.
Consequently, when sweeping the milled portion of a roadway that is wider than the fixed width of the broom assembly, a conventional sweeping machine must make multiple passes across the milled portion of the roadway to completely sweep the road surface. It would be desirable if an assembly of components could be provided by which the width of the sweeping path of the broom assembly of a vehicular sweeping machine could be readily and easily changed to allow the machine to accommodate brooms of different lengths. Such a modification would allow a single machine to be used for sweeping of roadways in a single pass, regardless of the width of the milled portion of the roadway.